| Project/Area Number |
61550363
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Hydraulic engineering
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| Research Institution | Hokkaido University |
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Principal Investigator |
SAEKI Hiroshi Fac. of Engineering, Hokkaido University, 工学部, 教授 (30001209)
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| Project Period (FY) |
1986 – 1987
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1987: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1986: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | reflection coefficient / standing wave / non-linear wave / Healy's method / electrical subtraction method / incident wave / 反射波 / 線の非線形性 / 波の変形 / みかけの反射率 / 消波構造物 |
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| Research Abstract |
This research deals with the reflection properties of non-linear regular/Qirregular wave due to structures ( vertical rigid structure and wave absorbertype structure). Experiments were carried out by means of dividing a wave tank into two channels. The ends of the channels had vertical wall and absorbing slope made from gravels and grass balls. In the case of separating incident and reflecting waves from waves in front of the structure, Healy's methodis usually used. But, it should by used for only linear or infinitesmal wave. At first, the author clarified the application limit of Healy's method by measuring the amplitude of node in front of the vertical rigid wall, and in the outer side of the application limit, reffection coefficients obtained from Healy's method coincide with the apparentreflection coefficients calculated from Tad; baksh & Keller's standing wave theory. Next, author determined the refiection coefficients by electrical subtraction method. The coefficients can be calculated from two wave profiles at the same distance from wave generator in each channel. The calculated reflection coefficients fiuctuated in accordance with distance from rigid wall. In the case of rigid wall, the reflection coefficients calculated from wave profiles measured at the node of standing wave are nearly 1.0. The coefficients calculated from wave profiles measured at the loop are larger than 1.0 and this phenomena occured due to the interaction between incident and reflected waves. It was clarified that electrical subtraction method calculated from the wave profiles measured at the node of standing and partial standing waves was very good method in order to get accurate reflection coefficient.
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